The invention relates in general to apparatus for transporting ammunition cartridges through a gun firing system and, in particular, to a transport apparatus that uses loops and couplings.
To convey ammunition cartridges, for example, 40 mm cartridges, through a weapon, a transport means is necessary to position and guide the cartridges through the gun firing system. The transport means may include couplings and loops. The cartridges are positioned in the loops and the couplings link the loops together. FIG. 1 shows cartridges 10 disposed in loops 12 that are connected by a coupling 14. FIG. 2 shows two loops 12 without the cartridges 10. The couplings and loops are physically shocked, pulled and distorted throughout the firing cycle and, therefore, require a certain strength to function properly.
FIG. 3 is a perspective view of a known loop 50 prior to assembly. Loop 50 comprises two parts 52 and 54. Part 52 includes a coupling interface 56 and side members 62. Part 54 includes a coupling support 58 and side members 60. FIG. 4 is a perspective view of the known loop 50 after assembly. In the known loop 50, the two parts 52, 54 are overlapped and then joined by welding. The side members 62 overlap the side members 60 and are projection welded in place, as at 64. There are also projection welds 64 on the opposite side members, although they are not visible in FIG. 4.
The weld joints 64 are one source of operational and production problems. During surface preparation, the assembled part 50 is bathed in cleansers, such as acid. The acid seeps between the overlapped side members 60, 62 and cannot be fully rinsed away. During long-term storage, the acid etches away at members 60, 62 and projection welds 64 and may ultimately cause failure of the loop 50.
The weld joints 64 are also prone to failure because of variables in the projection welding process, such as amperage, projection weld contact variations and surface preparation variation. The welded loops 50 must be surface finished, i.e., phosphated after welding. The weld joint 64 is difficult to phosphate. The strength of the weld 64 varies from vendor to vendor and set-up to set-up. Long-term storage of the welded loops 50 is affected by the lack of consistent coating at the weld joint 64, allowing rust to develop and degrade the weld strength. Manufacturers continually increase the price for the loops 50 because of welding and finishing difficulties.